Process for smelting sulphide ores to metal, matte, and slag



'5) ing in the lead, copper,

tain light-metal sulp them, such as M08 PbS, NiS, COS, Cu S, 75 r and FeS, for example, have a typically me- Herein tallic a pearance, whilst others, such as SnS, Chem formula, 33332, 33123:? gggf iagg .CdS, and certain zinc blends etc.-, containing 7 gaf iron sulphide, are of semi-metallic aspect, M and others again, such as pure ZnS, MnS, etc., MS 3 3 0 together with all the light-metal sulphides, i g have uiteanon-metallic appearance. Closer 882s; III 34.4 11.5 investigation shows that the hysical proper- 2 1 3 tiesof the sulphides agree airly well with gg 8-3 23-? Metallic their appearance. For example, the metal- 00%; e 2110 2119 85 lic sulphides conduct the electric-current in 522 $332, 33...

- s, ids

. just the same way as metals, without under- 12,;

going transportation of substance; whereas gdg. 34-: em l cthe non-metallic sulphides, in the molten 2 1 23' 43' state, conduct the electric current electrolytifigs $3 2 90 cally (that is to say, with transportation of 3 8933 32-3 substance). A'metallicproperty of certain sfsLII 331 cola Nonmetalllc. heavy-metal sulphides, which is ver imfig {g ortant from the metallurgical point 0 View, .Lhs 105 105 is their capacity for dissolving pure metal 95 Patented Mar. 1931 UNITED STATES PATENT OFFICEQ HARALD SKAIPEL, 0F OSLO, NORWA? raocn'ss For. SMEL'IING summer: 03118 no METAL, MATTE, mp SLAG No Drawing.- Application filed July 30,

This invention relates to process for spielting sulphide ores -to metal, matte and s a".

fll the existing metallurgical matte smeltmetal industries, operations are carriedon with the formation of slags rich in ferrous oxide (over 15% ing a high power of dissolving puremetal.

In contrast thereto, the present process contemplates the formation of slags poor in FeO, and in equilibrium thereto, mattes which conhides, thus facilitating a clean-cut separation between the" crude metal and the-matte. on my newly discovered principles with regard to the stratification and distribution of the elements in the metallurgical polyphase system: metal, sulphide, silicate; employed in combination with the old metallurgical smelting process. l

If the various metallic sulphides be regarded, in apurely superficial manner, in the crystalline condition, it is found that some of when they are in the molten state, and of being dissolved by. pure metal. 'In the sulphide series, this property diminishes as-the metallic nature of-the sulphides in question becomes less apparent. Thus, FeS, for example, 15 of 1928, Serial No. 296,414, and in Norway October-15, 1928.

and other non-ferrous of FeO) and of'mattes hav difference between a metal (M) and a sul- The process is based sulphides, that the heat of ormation plays an exceeding 40 cal. per gram-atom of sulphur 100 metallic appearance and, in the molten state and at a suiiicientlyhigh temperature, is miscible. with metallic iron to an unlimited extent. On the other hand, Al S for example, has a non-metallic appearance, and is quite insoluble (in the molten state) in pure aluminium, or other pure metals. Pure metals, such as iron and aluminium, are mostly miscible to an unlimited extent in the molten state. If investigation be made into the fundamental phide (MS), formed out of its components in accordance with the equation M S =MS X (in which X represents the heat of formation) ,it is found, by com aring the various important part, in accordance with the law that FThe metallic properties of the metallic sulphides decrease as the heat of formation per gram-atom of sulphur increases. In the following table, the most usual metallic 'sulphides are arranged in the order of the increasmg heat of formation per gram-atom of sulphur.

It appears that metallic sulphides with less than about 28 cal. per gram-atom of sulphur ossess metallic properties whereas metallic. sulphides with a heat of ormation are decidedly non-metallic. The table the alkali and alkaline earth metals and allmetals whose atomic weight does not exceed 40.07. The further peculiarity exists that, with few exceptions, all the sulphides are mutually soluble inthe molten state; and moreover, that themetallic character of such solutions of one sulphide in another depends in such a manner on the mean heat of formation per gram-atom of sulphur, that mixed sulphide melts with a mean heat of formation of less than about 24 cal. per gram-atom of S are metallic Whilst mixed sulphide melts with a mean heat of formation exceeding about 40 cal. per gram-atom of sulphur are non-metallic. (The numerical values of the mean heat of formation to be maintained for the mixed sulphides melts relate, here and hereinafter, always to aheat of formation,

- of FeS, of 24 cal. per gram-atom of S.) This discovery affords a means of controlling the stratification in the metallurgical polyphase system: metal, sulphide, silicate.

The present metallurgical practice is to operate with decidedly metallic sulphide melts (or mattes), which possess a high solvent power for pure metals, so that fractionated separation of crude metal from said mattes in the molten state can only be effected in a very imperfect manner. If however, in accordance with the principle enunciated above, there be added to such mattes so much sulphide with a higher heat of formation that the mean heat of formation of the sulphide melt increases to about 25-35 cal. or more per gram-atom of S, then the matte loses its property of holding pure metal in solution. The

' pure metal which was held in solution is transferred to a metallic phase which is sharply divided from the sulphide phase, even in the melt. For practical success with the process, it has been found advantageous to keep the sulphide phase covered with a silicate slag. The Stratification of metal and sulphide occurs very quickly and finely if care be taken, by a short thermo-electrolytic treatment,-in which the silicate phase is connected up as the electrolyte, and the sulphide and metal as the cathodeto ensurethe rapid attainment of chemical equilibrium between the phases. With a sulphide layer containing light-metal sulphides, however, this state of equilibrium can also be attained in the first stage of smelting, by selecting a suitable composition for thecha-rge and a suitable amount of added reducing carbon; and such method of smelting, with the results accruing therefrom, is the actualsubject of the present in- Vention.

therefore, a clean separation between sulphide and metal isefi'ected by the addition of a light-metal sulphide, the decrease of energy between sulphide and silicate is lessened at the same time, thereby increasing the mutual solubility of these phases. For this reason, the additionof light-metal sulphide must not be carried too far in operating with the three-phase system. It has been found of advantage in practice to maintain the mean heat of formation of the sulphide stratum between 25 and 35 cal., per gramatom of S.

A point of importance for estimating the decrease of energy between sulphide and oxide is my discovery that, in the oxide series also-though not in such a notable degree as in the sulphides there are members 'of 'a metallic, semi-metallic and nonmetallic character; but that the absolute values of the heat of formation of corresponding sulphides and oxides differ considerably, inasmuch as the metallic character of the metallic oxides evidently extends over a wider energy interval than is the case with the sulphides. It is well known that cuprous oxide is highly soluble in molten copper, although the heat of formation of cuprous oxide is 43.8 cal, at which level the sulphides, such as ZnS, MnS and A1 8 are completely non-metallic. The iron-oxide ores with heats of formation-of about cal. per gram-atom of oxygen, have a metallic and semi-metallic appearance. The boundary between semi-metallic and non-metallic, which in the case of the sulphides lies between 39 and 40 calories per gra1n-atom of sulphur, appears, in the case of the oxides, to lie between and cal. per gram-atom of oxygen. Zinc oxide, with a heat of formation of 84.8 cal. is pure white and non-metallic; and its position in the oxide series probably corresponds approximately to that of zinc sulphide (.43 cal.) in the sulphide series. At an energy interval of about 80 cal. per gramatom of oxygen between metal and metallic oxide, the solubility of the oxide in the metal has practically ceased to exist. Hence, in a manner analogous to that observed with the sulphides, a clean separation in relation to the metal phase (or sulphide phase) can also be effected in this case by sufiiciently increasing the energy interval between the phases by the addition of oxides with a higher heat of formation. In selecting the added oxides, care must be taken to ensure that the possess sufficient aflinity towards the oxi es with lower heat of formation present.

As has been ascertained by the inventor, the aforesaid conditions for a sharp demarcation, both between. metal and sulphide, and also between sulphide and silicate (or oxide), can be fulfilled in a. single smelting operation, by maintainin definite charging conditions in smelting. Ihe apparatus and performance of the operation remain substantially as at present customary, but the entire course of the smelting is performed, so to speak, in a different range of the metallurgical polyphase system metal,sulphide,slag, inasmuch as the degree of reduction (hereinafter more fully defined) of the system is substantially increased. In order to understand the relatlve condition-s in this connection, and to operate accordingly, it is necessary tobe well informed with regard to the various states of chemical equilibrium of the metallurgical polyph-ase system: metal, sulphide,

- silicate under diiferent conditions as to the content of oxygen and sulphur.

The chemical equilibrium of the system:

metal, sulphide, silicate,.may be regarded as the result of a contest of all the elements. for insufficient quantities of sulphur present and oxygen. In these circumstances, the elements distribute themselves among the various phases in sucha manner that the free energy of formation of the whole system atvtains a maximum. As has been ascertained,

the stratification of the system in the melt is also dependent on the energy of forma-.

tion of the various liquid phases, inasmuch as certain decreases of energy occur. both from metal to sulphide and from sulphide to oxide or silicate. these decreases forming the chief cause of the separation of the phases.

If sulphur be added to the system, then an equivalent amount of metal is transferred, accompanied by the evolution of energy, from the metal phase to the sulphide phase. If oxygen be added to the system, then an equivalent amount of metal is transferred, accompanied by the evolution of energy, from the metal phase into the sulphide phase, and at the same time the corresponding amount of metal is transferred from the sulphide phase into the silicate phase. If, on the other hand, oxygen be withdrawn from the silicate phase, by the addition of energy, the equivalent *amount of metal will be transferred from the silicate phase into the sulphide phase, and at the same time the equivalent amount of (other) metal will be given up by the sulphide phase to the metal phase. At the same time, both the transference of elements from the ass. phase to the sulphide phase, an the simultaneous cession of'met'al from the sulphide phase to the metal phase, take place in a certain serial order, inasmuch as the elements whose transference requires the smallest addition of energy to the system are the first 'to' be transferred. Usuall however,

several elements are transferre simultane- 'ously, but in different relative proportions,

according to their concentration in the phases and their position in the serial order of transference from silicate to sulphide, or from sulphide to metal. v

The inventor has previously described in his application Serial No. 694,609 a process which enables theamount of oxygen 'or sulphur in the molten system: metal, sulphide,

-' silicate, to be gradually lowered. so that the entire chemical equilibrium of the system is displaced. The 'experim ental performance of the process has therefore aifordedan excellent. opportunity of investigating the various 1 states of equilibrium ofthe metallurgical polyphase systemat various degrees of reduction. The process consists in employing the silicate phase (or slag). as electrolyte. The metal phase and sulphide phase are connected up as cathode, whilst a carbon elecployed as anode. switched on, the cations of the silicate phase :trode dipping into the silicate phaseis em- I When the current is migrate towards the surface of the cathode sulphide phase, and are there transferred, in a certain serial order, from silicate or oxide into sulphide. an equivalent amount of metal being ceded from the sulphide phase to the metal phase at the same time. The anions (chiefly SiO of the silicate phase migrate at the same time towards the carbon anode. where they are neutralized, by giving up oxygen which combines with the anode material and escapes as carbon monoxide. So long as the electrolysis takes this course, it can be typically-represented by the following reactions 1. FeS-l-MO +O=Fe+MS+CO+X kg. cal. (X is generally 2. Fgi ilh+C Fe+MS+Sl0 +CO+X kg. cal. (X is neg- If-tliese reactions be'established for the most important elements occurring in the silicate phase.( or slag) for example, for the decomposition of FeSthe differences in the heat effects per gram-atom of S furnish a survey of the serial order in whichthe various components of the silicate phase are transferred. In all these reactions, CO is liberated at the anode, and Fe is separated cathodically so that the difference in the energy required for transforming the elements from silicate, or oxide, into sulphide, may be expressed by the differences of the heat effects per gram-atom of S, and those components which require the smallest amount of energy for the conversion are naturally converted first. The-reactions such a way that one element is transferred are set out in the appended Table 2: only after the preceding one and in sharp TABLE 2 Perl m- Cal. atom o FS kg.cal. 1 re's-i-ino o= Fe-K1S co 1 10.4 +104 2 FeS-l-NagO o= Fe-l-NagS oo 2.5 as 3 res-+1350 c= Fe-l-BaS o0- 25.4 -4 4 FeSLi2O C= FB-i-LizS CO 29.8 29.8 5 FBS--C8O o- Fe-i-CaS co s21 -s2.1 a FeS--Fe0 o- Fe-i-FeS 00 36.5 36.5 7 FeS--Zn0 o- FeZnS co sac -so.s 8 FeS--Mn0 C- F6-M11S+ CO 40.1 --'40-1 9 FeS-Mg0 C- Fe-MgS+ C0- 58.9 58.9 10 ares-a110, --so-:re- 1u1s,+soo- -zso.1 -ss.a 11 3F8S-B203 3C=3Fe-B S; +300- 18l.3 60.4 I 12 2FeS-Si0 --2C=2FO--Si$1 +200- 129.8 64.8 13 mes-mo, --2c=2Fe--Tis, +200 (I) high 14 FeS-ZnSiO; o= Fe- 39.5 49.5 15 FeS-BaSiOa C= Fe- 0- 16 FeS--N82SiO:-- C= Fe- 41.6 -41.6 17- FeS-FeSiOa c= Fe- 45.4 -45.4 18 F6S-MnSiO3" C= Fe- 45.5 --45.5 19 F8s C8slO; c= FB- 49.0 -49.9 20 FeS--MgSiO;-- C= Fe- (?)about -71. 21 4FeS--AliSiz01-3C=4Fe 214.3 48.6 5 22 3FeS--AliSi;O1-3C=3Fe-l-AlgSg-HS10:+3CO -2e5.e 88.5 23 FeS-Li1Si0: o= Fe+Li 94.8 -94.8 24 2FeS-1-LhSi0s+2C=2Fe+SiS1 +L i,o +200 1e4.s -91.4

The reactions 1-10 furnish an idea of the differentiation from the latter, but the matter c0nditions, ar1sing when the oxide phase, or is one of a displaceable chemical equil bsilicate phase, is highly basic; whereas the rer1um'ad ustable within small 111tervals1n actions 11-24 correspond to the conditions which the distribution of the elements preswith-neutraloracidsilicatephasel Theditferent, in silicate, sulphide and metal is deterence between basic and acid slags isparticib mined, and by the degree of reduction fixed larly small in the case of aluminium (reacfor the time being. From this it s clear that tions 10 and 22) and particularly great in the degree ofreduotion is determined by the the case of lithium (reactions 1 and 23). last element transferred into the sulphide From the heat effects of the reactions 1418 phase; so that, in theory, there are as many it is evident that the metals zinc, barium and degrees of reduction as there are elements in sodium are situated, in the serial order of the transference series. This simple fact was transference, from silicate to sulphide, closely previously unknown in metallur and ts in front of the position of iron, whilst mangadiscovery enables the metallurgical polylphase nese, on the other hand is beyond, whereas calsystem to be dealt with in quite a di erent cium and magnesium require moreand alumanner from heretofore, inasmuch as it is minium very much -moreenergy for their poss ble by maintaining certain degrees of retransformation from silicate into sulphide. duction to drive over certain elements com- In connection with the present process, it is pletely, fore zample into the sulphide phase, 7 highly interesting to note that theposition of If their position in the transference series be the light metals potassium, sodium and bakn wn, 01' determined by preliminary experir1 um 1n the serial order of transference from ment. silicate to sulphide is before-or near to that If, for example, amolten mixture of oxides, of iron, that is-they-are converted from silior a silicate phase, be added to molten iron cates to sulphides with a smaller consuinpsulphide-such addition containing a suflition of energy than iron,- thereby affording a oient amount of oxides of other of the nobler means ofsmelting a matte containing lightheavy metals, in addition to the usual slag metal sulphides, which is in equilibrium with const1tuentsthen, as is known from the oldthe slag, even in cases where the slag contains er metallurgy, the major portion of the heavy relatively large amounts of ferrous oxide. To metals nobler than iron, will be transferred do th1s,'all that'is needed is to add sufiicient from the silicate phase to the sulphide phase, amounts of the said 11 ght. metals to the system. by a' purely chemicalreaction (expressed by Practical'tosts confirm the serial order of the equation Cu O+FeS=CugS+FeO) betransference from silicate to sulphide: inditween the silicate phase and the sulphide catod by the table, which 18 approximately as phase, inasmuch as they are replaced in the follows: I silicate phase by the equivalent amount of Nobler heavymetals (for example Pt. Au, iron. In this manner, a silicate phase is ob- 12 A A Sb, M0, N1, 00, Cu, Pb)-Zn, tamed of approximately the same composi- (S K, Na,-Ba,Fe,-(Cr.) ,-Mn,- tion as the ordinary slags of matte smelting, 'C .-Mg, 1). which are rich in ferrous oxide. In this case,

Of course, in carrying out the process n the E38 content of thesulphide phases forms, a practice, this serial order does not occur in as it were, aguarantee against the slagging of" 1 30 metals as occu y a position near that of iron in the series transference from silicate to sulphide-for example, zinc, manganese,

' chromium, etc.-will remain-like the iron' in any considerable quantity in the silicate phase. If this silicate phase be still further reduced, for example by the previously'mentioned thermo-electrolysis, transfer from silicate to sulphide will be chiefly effected in the case of iron, at the commencement of the electrolysis, accompanied, however, in certain relative proportions, by the said heavy metals, Zn, Mn, etc., and also by light metals such as potassium, sodium and barium, which can be transformed from oxide into sulphide just as easily as iron. At the same time, the already low content of nobler heavy metals in the silicate phase will be still further lowered. Not until the reduction has proceeded so far that the content in the silicate phase of(FeO +FeS)has been reduced to acertain extent-to about 7% FeO+FeS in basic slags, and oonsiderab y less in 'acid slags-'do any notable amounts of calcium and magnesium begin to be transfonned into sulphide. At the same time, FeS ceases to act as a preventive of the slagging of nobler grouped into the following stages of reduc-' .50

down to about 7 as, in this stage, protection'agamst heavy metals, this role being assumed by the content of calcium sulphide and magnesium sulphide in the sulphlde phase. As reduction progresses, especially when the amounts of calcium oxide and magnesium oxide inthe silicate aluminium oxide, begin to pass over into sulphide in notable amount. By carrying the reduction further, the entire oxide, or silicate phase may, in certain circumstances, be com pletely eliminated.

- It follows therefore that the distribution of the various elements in the three-phase system: metal, sulphide, silicate, varies with the above defined degree of reduction of the system, and, in respect of the relation between slag and matte, and with reference to the i components usually present in the slags and mattes, the entire system may be suitably tion 1. The ferrous'oxide stage, which is char acteri'zedby a silicate phase rich in FeO- FeO- and by a sul hide phase which is almost free from 0:18, gS, A1 8 etc., but mostly rich in FeS, inasmuch the iron sulphide forms the the oxide slagging of the nobler heavy metals. If the silicate phase be acid, the limit of the stage'is reached with far smaller contents of ferrous oxide than specified above. In this stage, a considerable per- I centage of the baser heavy metals, such as Zn,

etc., is taken up, or slagged, by

together with ferrous oxsuch asK,

Sn, Cr, Mn, the silicate phase, i'de; whereas certain lightmetals,

phase have become very small, the more difiicultly transferable oxides, such as example, Zn, Sn, Cr, Mn,

-ores, co per-,.zinc-, silver ores, ores an others in sucha manner that a sysextensively transformed into sul hide, to-

gether with the light metals K, Na, a etc., to an increased extent. In this stage, da-S and MgS form the protection against oxide slagging of the nobler heavy metals, which is con-' siderably lessened by comparison with the first stage. r

3. The aluminium sulphide stage, characterized by a silicate phase or oxide phase which is low in FeO, CaO and MgO, and is constituted by the light-metal oxides or silicates (such as A1 0 etc. which aremost difficult to transform into sulphide, and of a heavy-metal sulphide phase containing A1283, ifv any heavy-metal sulphide be resent. Light metal oxides of K, Na, Ba, a, Mg, etc., can be transformed into sulphides in this stagc'almost completely. Silicon, aluminium and lithium can also be extensively transformed into sulphide or to the elementary condition, in this stage. 7

These groups, or stages, which broadly indicate the serial order of. transformation of silicate into sulphide, can, of course, be further sub-divided as desired, inasmuch-as already mentioned-as constituent of the silicate phase, a certain (adjustable) degree of reduction of the system, at which it is transformed into sulphide in a practically complete manner. Re arded from this standpoint the hitherto nown metallurgical treatment of the non-ferrous metals is uneconomical insofar as on an average, slags, which are very rich in ferrous oxide, (containing from 18 up to over 50% FeQ) are employed, that is to say, slags of an extremely low degree of reduction and thus a correspondingly high oxidic slagging both of the more noble metals (such as for example, Ag, Cu, larly of the baser heavy meta)ls .(such as for etc.

In contradistinct onto this, the present invention contemplates altering the course of the melting in the-smeltin of for example, vcopper ores, lead ores, lea zinc-, copper? complex tin tem of a very high degree of reduction-more closely defined "'as slagging-1s employed,

which contains from 15% to 0% FeO and vmattes containing-from 1.5 to 20%,and in certain cases lessthan 1.5% and more than there exists, for each Ni, Co, Pb), and particuacidity of the slags increases their solvent properties for sulphide decrease- By increas ing the degree of reduction a more complete transformation of the desired constituents into sulphide is thus obtained and by increasing the acidity. of the slag the result is ohtained that the (metallic or non-metallic) sulphides formed substantially collect in the matte. If it be assumed that'slags of these three stages are in contact with mattesof one and the same composition, then the decrease in energy hereinbefore referred to between silicate phase and sulphide phase in the ferrous oxide stage 'is at a minimum, and

is greater in the calcium sulphide stage and at its maximum in the aluminium sulphide stage and the greater the decrease in energy e the more complete is the separation of' phases.

In cases where on y the two phase: sulphide, silicate, system is being worked up the same considerations ariseas in the three phase metal, sulphide. silicate system. However also where the sulphide phase is absent,- that is to say, in the metal, silicate, system, similar considerations must be taken into account and there is a transformation series of the elements from silicate or oxide to metal. In a few individual cases, this occurs 1n metallurgy without the principles in question however, being clearly recognized. The

best proof of this, is the existing practice in the metallurgy of tin ores, where on an 'average slags rich in ferrous oxide (18 to 50% Fe) were employed and as a consequence slags were produced even after twice smelting, which contain not less than 2 to 3% of tin. In the metallurgy of tin the recognition is obviously lacking, that the tin in the series of; tra nsformation from silicate or (we ide to metal is so closely in front of the position of iron that a complete de-tinning of the slags can only take place with the simultaneous lowering of the ferrous oxide content of the slags. 'By. increasing thedegree of reduction of the tin slags it is easily possible, according to the present process to produce waste slag's containing far less than 1%oftin.

Since one of the most important functions ofthe ferrous'oxide content of the present matte'slags is that of serving as a flux for lowering the melting point of the slags it is necessary in the present new process to for FeO.

produce a melting point-lowering substitute Such melting agents may be alkalies, particularly Na o, which can be added in the form of any cheap salt. A content of 3 to 10% alkali in the melt is usually sufficient for this purpose. Similarly, in order to lower the melting point of the mattes when they have a high content of diflicultly fusible sulphide, suchas for example ZnS, MnS, M08 it is possible to use in addition to other sulphides, alkali sulphide which at the same time produces the desired reduction of the dissolving power of the mattes for pure metal. By virtue of the com-v position of the charge and the degreeof re duction of the system determined thereby,

the result is attained that the added alkali salt etc-., is (ll"l(l6(l up into desired portions between slag and matte. It has been-shown, that the additlon of alkali hasan extremely favourable effect 011 the course of the reactions insofar as t acts, so to saeak, as a lubricant, so that the reactions ta e place at considerably lower temperatures than otherwise. The action of the added alkali is particularly noticeable when reactions analogous to those set forth in Table No. 2 are tofollow a purely thermal course. The partic- 4 ularly important reactions take place only at very high temperature bea metallurgical sense for the desulphurization of iron, are of'little use in the metallurgy of the non-ferrous metals. In the presoint-lowering ence of a certain amount of alkali they take place smoothly and with case at 1100 to 1400 By virtue of this, these reactions ac ui're a new utility and they open up new fiel s of use. .A particularly novel and important application lie's in'the employment of thereactions in order to separate out'fractionally one or more meta-ls according to the present process, as crude metal from uni-casted sulphide ores. For this purpose it 13 possible to supply with advantage as an example of material containing CaO: and MgO, bas1c blast furnaceslags or slags obtained in the production of steel, and-alkali, for example, in the form of a suitable mixture (Na SO,+carbon) About 10% l\la- .SO of the weight of the slag is sufficient. The slag is advantageously comminuted and mixed with the ore which is likewise comminuted and if desired preliminarily treated to bring same to .the low'est possible stage of sulphurization, and .is also,

.in-shaft furnaces or electric furnaces.

mixed with coke and sulphate andthe mix-' ture is, if desired, agglomerated (or briquet-, ted), by moistenin and drying the same prior to smelting. he smelting can be carried'ou t 'in known manner and particularly larger amounts of Gas or MgS render both mattes and slags diflicultly fusible, it is possible, in accordance with the principles 1iereinafter explained, by the simultaneous addition of old matte slags, rich in ferrous oxide and in the form of pieces, to provide for retransforming Gas and MgS into CaO and MgO, which pass into the slag, (see for'example, Example No. 1 below).

From the foregoing explanation, numer ous practical conclusions can be drawn. If,

,for example matte'slags rich in ferrous oxide are smelted together with material yielding Gas or MgS, for example CaS, anhydrite or gypsum and carbon, lime and material yielding sulphur, magnesium sulphate and carbon and the like, the transformation takes place during the melting down whereby the bulk of the iron content of the matte slag is trans formed into sulphide and forms matte in accordance with reactions analogous to the equations res1o.+cas=casio. +FeS FeSiOa+MgS=MgSlO;+FeS inasmuch as the said matte is replaced by CaO or MgO in the slag. The operation represents on the one hand a process for utilizing the sulphur content of calcium sulphide, gypsum, anhydrite, etc., this being found to combine with iron or other heavy metals in which form it can be rendered useful in known manner by roasting, and on the other hand a process for the extraction of iron and other heavy metals from silicates or sla-gs inasmuch as these heavymetals are also transformed into sulphur compounds adapted to be more easily worked up. Simultaneously the slag is converted from ferrous silicate into the more valuable calcium or. magnesium sihcate which on suitable ad ustment of the composition eitherdirectly or by subsequent. treatment (in the fused state),

can be withdrawn as a valu. ble product for example for cement, glass, brick, raw material forthe manufacture of alumina etc.

i In the direct smelting of sulphide ores rich in sulphur to form matteand slag, the distillable sulphur can be absorbed-by the mixture of lime or limestone for example accord- ,ing to the equations:--

2 050 +3 s =2 cas+so,

2 CaC0;+3 8 =2 eas+so,+2 co. 2 oaoo,+2 s+o=2 058+?! 00, and the freshly formed CaS can be caused to react with old matte slags and to transform them into calcium silicate low in FeO whilst extracting the content of iron and heavy metal in the .form'of sulphides; This rerich in ferrousfloxide, by

Since action can also be utilized the purpose of and heating the mixture, the calcium or magnesium sulphides then reacting with the slagsrich in ferrous oxide.

' Aparticularly important field of applica-- tion of the double decomposition between Gas and MgS andferrous silicate is the direct working up in the fused state, of the slag derived from the smelting of-matte, rich in .pyritic ores and carbon to the said ores ferrous oxide as obtained from the present smeltingprocessespinto silicate with a low ferrous oxide content and a fresh matte which retains practically the whole of the content-of the more valuable heavy metals.

such as Cu, Pb, Ag, Sn, Zn, etcl, remaining inxthese slags. The operation is preferably carried out in a fore hearth which is heated electrically or by other means and the operation ofmixing CaS, MgS and if desired, alkali sulphide with the slag is facilitated'by the further addition ofFeS or eomminuted poor matte (if desired of the same operation) which produces a sinking of the light metal sulphide in the melt. The slag is according- 1y so to speak, treated by a double matte and is therefore extracted to a very great degree. By maintaining a definitely high degree of reduction. (for example by means of MgS) it ispossible in the second matte. under certain conditions. to cause the valuable rare elements present in the first slag such as for example. vanadium, tungsten, gallium. etc., to be deliberately driven over into the matte.

Example No. ]-A complex ore showed on analysis, the following cpmposition:

' 35.4% Pb, 9.4% Cu, 11.7% Zn. 4.9% Fe, 0.9%

As, 17.1% S, 16.3% SiO- 1.2% A1 0, 1.1% CaO, 1.7% MgO. The ore was comminuted and mixed with 10% of quick lime, 10;

Na SO. and.6% of powdered coke, agglomerated bymoisteningand drying andwas smelted in a shaft furnace. with the further addition of 20% slag rich in ferrous oxide, in known manner by means of coke in the form of pieces. An acid slag poor in ferrous, oxide and having a very low content of heavy metal was obtained. together with the following products which could be separated by tapping that in consequence of the content of light metal sulphide in the matte, in this method of carrying out] the. smelting, matte and speiss can be separated in a fluid state by tappin off from the fore-hearth.

E vample N o. 2.-A foundry had available a calcareous zinc ore of approximately the following composition 9.6% Pb, 9.8% S,2.6% SiO 66% CaQO which was of such anature that it could only be dressed with great -.difficulty. The same works had at their disposal from a lead shaft furnace operation, unlimited amounts of old slags of the composition: 37.5% SiO 28.4% F e0, 7.8% A1 0,, 14.7 036, 3.3 MgO, 3,2 ZnO, 0.7% PbO, 0.4% Cu. Duringthe treatment of these products according to the present'process, it was atttempted-to collect the zin'ccontent of the ore and the slag in a matte whereas the lime content of the ore was 1n- .tended to be converted into CaS byheating with the addition of imported iron pyrites of the a proximate composition: FeS 6% Zn 2% Gus, 1% bS and 16% SiO in order subsequently to cause it to react with the F eO content of theslag. In order to reduce the meltingpoint of the matte it was treated so as to contain N3 3 by the furt er addition of sodium sulphate and carbon whilst simultaneously the melting point of the slag was reduced'by taking up Na O"and it was prepared for conversion into bottle glass.

Accordingly lton of ore in a comminuted statewas mixed with 1.5 tons of iron pyrites, 150. kgs. of sodium sulphate and 130 kgs. of coke powder and was agglomerated by moistening with water and subsequently drying. The whole was then fused in a shaft furnace together with 1.5 tons of old slag and coke, and about 1.87 tons of matte having the composition: 73% FeS, 17.3%- ZnS, 3.7% PbS,

2.7% Cu S, 2.5% Na S, and 0.5% CaS, were '60 bon in suite tion the tin, tun ten and iron contents of the obtained. This matte was worked upfin known manner by crystallization, disintegration and dressing into'zinc blend, magnetic pyrites and copper-', 1ead-, silver sulphideconcentrate andin addition about 1.65 tons of sla having the composition 48.7% SiO 7% .0 35.1% 0.10, 3.2% M o, 3 F80, 1.2% at 1 S, were produced. Such a slagcan he worked up in another furnace into-bottle glass, building brick orthe like, after suit-, ableadjustment of its composition.

Example 3.A tin slag from a reverberatory furnace smelting operation contained: 33.4% Si0 ,14.7% A1 03, 23.2% FeO, 7.9% CaO, 0.5% MgO, 1.7% Na,O, 8.1% SnO', 1.3% WO,,. It was smelted together with a mixture of g psum, sodium sulphate and car- 510 proportions. In this operaslag were trans erred to a matte containing sodium sulphide which was worked up n known manner into tin, tungsten and iron sulphide.

, 1.2% ZnS, 0.16% Pbs and 0.13%

A further very important application of the process consists in working up certain oxidic ores into sulphides and slags with the I aid of material which yields CaS or MgS and in particular ores which contain such oxides of heavy'm'etals which he in the 'vic1n1ty of iron or after iron 1n the serlal order as forexample, the chromium and iron content of chrome'-1ron-stone, the manganese content of lmpure manganese ore (contaming for example sulphur and phosphorus) the iron and a great part of the vanadium content of titanium-iron ores and the like. The process may also, so to speak, be carried out in a fractional manner, insofar as at first only certain constituents are transformed into the sulphide phase by the sparing apportioning of the CaS added, and other constituents are thereupon transformed into a new of transference from oxide to sulphide, such the freshly'formed light metal sulphide, since the light metal sulphide would otherwise dissolve in the silicate slags, particularly when the slag is, basic. FeS is particularly suitable as a solvent for alkali metal sulphides. However in the production of these light metal sul hides a separation of the silicate phase and sulphide phase can be entirely disregarded, since these light metal sulphides are all water soluble and can therefore be subsequently extracted as a solution from solidified and disintegrated melt by lixiviation with water. In this case it is moreover unnecessary to heat the mass to complete fusion, since a moderate heating up to sintering and transformation is suflicient.

Example N o. 4.A re ared leucite from Italy contained 18% E 6 2% Na O, 23%, A10 0 57% SiO it was finely disintegrated together with 35% of gypsum and 7% of coke andwas heated to sintering in a closed furnace, the gypsum being reduced to CBS whichag'ain reacted with the potassium content of the leucite. After cooling and disintegrating it was possible to lixiviate from the melt with water not only the potassium sulphide formed but also a large part of the A1 3 content of the leucite which entered into solution as potassium aluminate. From this solution 311 x120. can be obtained in known manner.

On the further addition of a ool'hill amount of CaO to combine with the lilbic mation'oi the matte regulated and memos acid during the sintering process, the yield oi otash and alumina is increased.

i already formed GaS is employed for reaction with leucite instead of gypsum and coke, the result is obtained that the transformation takes place at a much lower temperature, for example at 300 to 400 C. This result can be obtained by way of example, at-

a still lower temperature with the aid of an aqueous solution of Gas if a suitable moistened mixture is heated for a longer period with or without the employment of pressure. This process possesses the great advantage over the known process for the utilization of leuoite by heating with Gal) that Gas has a stronger tendency to react with silicate than CaO whereas on the other hand the freshly formed K 8 has not such a strong tendency as K 0 to be converted into the form of silicate.

As has been previously explained, it is possible, by means of the present process, in contradistinction to the former metallurgy, to obtain a clean cut separation in the liquid melt between sulphide (matte) and pure metal, by increasing average heat of forrsm-atoin S up to 28 to 35 calories or more by the introduction of light metal sulphide. By employing this principle in the decomposition of niattes of diverse composition, the inventor has been enabled to obtain abetter survey of the serial order oi decomposition or metal from sulphide, i. c. over the partition of the different metals between sulphide metal, than has hitherto made available by metallurgy. Moreover the-very important fact has been disclosed that the metallurgical speisses are in actual :Eact crude metals and not as has been hitherto assumed, matte-like products in which sulphur is replaced by arsenic (compare Ullman, Encycloplcdia Techn. Chemie, vol, '2', pages 423 and 412s). Whereas hitherto mattes and speisses have been tapped 05 together as a solution of liquid melts which only separated out into two layers in the tapping receiver on cooling, the method of conducting the smelting operation according to the present process however, yielded a cleancut separation between matte and speiss even in the fused condition so that they could be separated from one another by tapping.

Moreover numerous comparative tests demonstrated that the speisses according to their composition occupy a definite position in the serial order of precipitation of metal from the sulphide phase. This knowledge, in conjunction with he serial order of precipitation, established by the inventor, i. e. the partition of the difi'erent metals between metal layer and sulphide layer, enables the amount and composition of the s eiss obtained to be moreover iscloses a novel and economical method or" worh'ng up speiss of valueless composition such as is frequently obtained in present day metallurgy.

justed degrees Experiment llo.

The serial order of precipitation of the most customarily occurring heavy metals from a sulphide phase of the most diverse composition might beapproximately the following Mo, As, Sb, Ag, 1300"), Go, Ni, Fe, Cu, C1, (Z11 below 1200 (1), Mn. It is however, in this case, not a question of a well defined serial order, but of chemical equilibrium between metal phase andsulphide phase, which lead to the most diverse ratios of partition of the diiierent metals between sulphide and metal, according to their position in the serial'order of transference, their concentration in the system, and the degree of sulphidation of the system. By altering the latter the whole equilibrium can be displaced in one or other direction.

The serial order of precipitation is therefore in itself, insuificient as a basis of operation, inasmuch as for metallurgical operations the data relating to difierent definite states of equilibrium between metal phase and sulphide phase are necessary. For example, given a matte oi the approximate composition 47% PbS,12.9% (lu s, 19.8% Zns, 8.5% FeS, 0.84% As and about 10% (Na S and GaS), which is subjected to decomposition by the removal of sulphur (for example by thermoelectrolysis), raw lead is first deposited until the lead content of the matte has been re duced to a definite quantity, which is interdependent upon the iron content of the matte. In the case of a higher iron content, if the lead content or" the matte has been reduced to 10% to 8% 7 b, both lead and iron are deposited in considerable quantity. The limiting values correspond to a lower lead content in the case of niattes with a poor iron content. From this stage onwards iron also separates out in addition to raw lead, which as is well known is not miscible with lead,

layer above the lead. The following analysis taken from the experiments of the inventor show the partition of the different elements between matte and crude metal on smelting their raw materials at various ador" sulphidation; incidentally 1 shows the case in which the sulphide phase has not separated 0E until metallic iron has appeared, and Experiment No. 2, shows the case in which the separation was continueduntil iron (-speiss) made its appearance.

, Ewperimcnt N0; 1

Raw lead Pb not determined Pb, Sn, (Zn above 76 Eaiperimeat No. 2

Rawlead the arsenic is distributed between matte and raw lead in the ration of about 1: 8.2 as long as no 1ron separates out. During this period I the raw lead is simultaneously speiss, as it were, inasmuch as it takes up arsemc. .VYhen.

however iron. commences to separate out it thereupon extracts the bulk of. the arse 1110 from the rawlead and from the matte and is converted into a speiss as can be seen from Experiment No. 2. The partition ratio of the arsenic between iron, raw lead and matte shows a large-preponderance in extraction by the iron, as can be seen. As is Experiment No. 2, crude metallic iron free well known, iron is miscible to anextremely slight extent with the ordinary nonsferrous metals such as lead and copper (and also tin) and forms a separate phase in-the fused condition, side by side with these. Metals which in the-simultaneous presence of iron sulphide, metallic iron and non-ferrous metal, preferably collect in the iron phase, areadvantageously classified as siderophilic elements. Such siderophilic elements contain inter alia the following elements :"Ni, Co, Pt, Mo,As, Sb, P, C, Si. The mutual 'solubility of matte and speiss in the fused liquid state, known in present day metallurgical practice, is due to the fact the mattes hitherto contained practically no light metal sulphide and therefore ossesseda high solvent power for pure meta s, particularly for iron and siderophilic metals. The separation of such s eisses from matte in the fore-hearth according to the hitherto .usual practice is a similar phenomenon to the known eliquation. of metallic iron from its solution in FeS, by

cooling. If no arsenic had been present in from arsenic would have commenced to separate out as a separate phase at approximates ly the same temperature at which the iron speisses commenced to appear. For example, from a lead matte containing 5.85%

Pb, 20.6% Fe, 28.9% Zn, and about 10%- (Na 'S+C.a) etc., a crude iron metal containing only 0.3% As was obtained together with crude lead, Experiment No. 2, shows that iron is an excellent collecting1 medfium 'ty 0 exfor arsenic anddiscloses the po'ssibi tracting thelarsenio content from arsenical raw lead-to a high degree, by the addition of some iron, and of recovering the same in a 1 concentrated form.

The experiments moreover disclose, the

possibility of a new form of the old 'precipitation process for lead, consistin in adding to the matte a certain amount of ight metal sulphide, whereby the removal of lead from the matte to a lead-content of less than 8% can be efi'ected. They furtherdemonstrate the possibility of employing in this process iron speisses or copper speisses or copperlead speisses instead of-iron. In the latter case, it is possible by suitably adjusting the proportions, for example by the addition of an excess of speiss,.to insure the production of small amounts of a fresh speiss of advantageous character, for example of iron speiss which acts as a collecting agent. for the siderophilic elements present.

'lhe two experiments also show the artition of the'copperbetween the raw lea and matte (Experiment No. 1) and crude iron metal and matte (Experiment No. 2). Fromthese and other experiments in the presence of large amounts of iron sulphide and metal-j lic iron, a partition ratio of the co per between matte and crude metal is o ta'ined, which lies between 1:10 and 1:6, generally however between 1:9.5 and 1.8. If for ex ample no iron had been present in Experi ment N o. 2 the copper would have commenced to separate out when the matte had a lead content of about 1% Pb and would have ex-' tracted the arsenic. from the raw lead and matte, forming copperspeiss. Copper and lead are only miscible to a limited degree, but the presence of arsenic increases the miscibility, so that these copper speisses take up a considerable lead content from the raw lead simultaneously deposited. Such speisses are for example those which according, to Ullman, Encyclopaedia Techn. Chemie, vol. 7 page 428, fall within the definition of ochre hav ng a compos1t1on:

Rich Poor speiss speiss Per cent Per cent Cu 51.73 25.86 Pb- 35.20 mos F8 1. 65 22. 17 1 2. 4.04 Sb a a4 13. 50 Ni-I-On o. 37 2.71 Zn- 1.83 an AB-l-All 0. 175 0. M5

p and which are at the present time worked up with difiiculty in speiss furnaces. In view of? the position of these speisses in the serial order of precipitation of metal from the sulphidephase according to the present process,i

'- it might be'possible to obtain the precipita-' tion of speisses of suitable composition, for

example of ironspeisses even during the smelting. These speisses may however be worked up as such with-the greatest facility,

by causing them to react with a'matte con taining light metal sulphide and PbS or FeS for example, in accordance with the present rocess the'copp'er content reacting with Pb or Fefor example, (-Pbs+2ou=0u.s+1 b= FeS+2Gu= Cu S +Fe)" and forming matte, whereas the lead content of the speiss enters the freshly formed raw lead derived from the matte. he separated iron forms with the siderophilic elements As, Sb, Ni, Co, a fresh s l tageous properties. e noble metals mainly, enter the raw lead whilst the zinc enters the matte.

tallic. heavymetal sulphides to a consider-'1 able'extent, if the tem eratum be maintained. of the silver between matte and raw lead at sufficiently low. At igh temperature however, the volatility of the zinc becomes apparent since at such temperatures it is set free by the same metals which it was capable of reducing from their sulphides at lower temtant reaction:

- is a reversible reaction which at lower tem- I peratures. proceeds from right to left to a great extent but which obeys the law, of mass action. .Accordingly.

. [ZnS] p m e ant.

whereas above 1300 G. zinc volatilizes to a high degree.- InExperiment No. 2,-1the-te'm perature was accordingly maintained at about 1200 to 12509 C. in order to collect the zinc in thematte-and thistest showed that it is actuallypossible to collect the zinc in "the matte as-su'lphide in the presence of metal- ExperimentNo. 2 was notdetermined but judging from experience of other tests might have'amounted to about 1 to 2%; In another case the following distribution of the eiss with more advanperatures. Thus for example in the imporzinc (and copper) between matte and raw' metallic iron was found:

Matte-- Zn, 18.4 Cu. Raw me oiron-.0?i1% Zn, 1.59% Cu.

In th'e reduc tion of ZnS by means of copper at low temperatures slightly more zinc enters the metal, apparently 'becausezinc possesses a certain aifinity for metallic copper. A test in this case gave the following results sulphide a e-flaw zns (=2s.a% Zn), 56.2% ems,

about 8% rats. Metal layer-.10-12% Zn, 89% Cu.

From the given determination of the position of zinc in the serial order of transferonce from sulphide to metal the new fact is thus apparent that on the one hand vzinc can be collected as presence of metallic iron at temperatures below about 1250 C. At temperatures above 1250? 'C., on the'other hand, metallic zinc is liberatedby the action. of iron and other heavy metals.

Experiment No. 2 also shows the partition a low silver content. The partition ratio is about 1 :7. In another experiment with pyrites rich in silverthree products were 0 tained, namely:

1 Matte with 2.9% Ag.

2.- Crude metallic iron with 0.09% Ag. 1 3. Crude silver 24.6% Pb.

The partition the nickel between a matte rich iniron sulphide and raw metallic iron can be" seen from the following equilibriummass obtained by experiment:

'Matte..44.67 r' 4.14 Ni,14.5% Cu, 107 a 54-055). Iron -82% r8, 11f1 1, 2.5% cu. i (N The partition ratiois thus about 1:4 and shows thatrelatively high percentage ferronickels or nickel-steels low incopper can be" fractionally' se arated directly from natural. magnetic nicke ing about 2 to Cu with the aid of the present process.

1 The partition ratio of molybdenum between iron sulphide and metallic iron. is still more favourable for such direct production of ferrous alloys. A test showed:

whichcontained' only 03% Mo.-

present contained only 0.05% M0.

Thebove explanation should be the most commonly-occurrin metals from lic iron. The zinclcontent of the speiss in n with the aid the smelting principle it is easily possibleby suitable experiments also to arrange the rare metals in the series.

speisses sulphide in the matte in the V with 72.4% Ag andpyrites concentrates contain 6% of nickel and 1 to 4% oi i During h operation the silicate phase simultaneously v s'uflicient' V to clear up the senal order of precipitation of traction of treatment of these alone with 'ble of'application to the and antimon in this serial order of precipitation, it has een established that in this connection there are three main classes of speisses which appear in sequence during the continued splitting up of a complex lead, cop per, iron matte, namely:

1. Raw lead containing As and Sb (lead speissl) 2. ron speiss or crude metallic iron,

3. Copper speiss or copper-lead speiss. Iron speiss appears to possess the most favourable metallurgical properties amongst these, because on the one hand, it only takes up extremely small amounts of lead and copper and on the other hand because it. attracts in addition to arsenic other siderophilic elements such as for example, Ni, Co, Mo, Pt etc., to a high degree. In certain circumstances it may also be advantageous to bring one and the same matte or raw lead into contact with poor speisses in sequence, that is to say, with raw metallic ferrous metals for the more complete-extraction of the siderophilic elements. The counter-current principle can be advantageously employed however, in this case. Moreover in such case, the composition of the iron employed for the speiss formation 1plays a certain part inasmuch as if the speiss ormed contains carbon, it separates more sharply from the non-ferrous metals than speiss poor in carbon. Raw metallic collector for certain carbide-forming side rophilic elements such as for example vanadium, molybdenum, chromium, etc. than that poor in carbon and has moreover the advantage of a lower melting point than said latter. In certain circumstances, phosphorous may also be employed with advantage as the means for lowering the melting point. e In stead of effecting the speiss formation by direct reduction, during the first smelting, it can also be efi'ected by the direct addition of for example, raw iron. Moreover for the excertain elements from sings, a raw ferrous metal, may be advantageous,thus for example a large part of the vanadium content can be thereby recovered from the smelting of Mansfeld copper schist by bringing said latter in a fused condition in contact'with-iron whilst-simultaneously increasing the degree .of'reduction of-the slags;

In general, the new state of knowledge i above referred to, which is essentially based on the fact thata clean separation between the matte and the raw metals is attained by the light metal sulphide content of the matte, permits of operation to a far greater extent than "hashitherto been possible with the polyphase syste'mQslag, matte, raw ferrous metal and non-ferrous metal. Besides being capanon-ferrous metals (for example Pb, Cu, Sn) where apart from .these latter, raw ferrous metal is also en 11011 containing carbon is however, a better crevice sla matte, raw ferrous er that certa1n coniil process is naturally most suitable for raw materials containing sulphide, for example, sulphide ores such as magnetic nickel pyrites, molybdenum glance, and the like, ly roasted sulphide ores 0r oxide a high sulphur content orcomplex iron ores, inasmuch as fractional precipitation of the metals in the presence of a sulphide phase effects an. advantageous division. A'ver important advantage of the process, resides in the fact that in the case of materials very rich in sulphur or raw metals, sulphide phase of the system can exert a desulphurizing action upon! the raw metal by taking up metallic sulphide. Thus for example, iron can be desulphurized even down to the extent-of 0.3% S by contact with an iron sulphide phase containing light metal sul= phide. This desulphurization need not necessarily be carried out during the first smeltin operation, but it may also be effected by incompleteores having the light metal su sequent treatment iof the iron which contains sulphur, in a 01 :-hearth in a three phase system according to the present process; light metal sulphide being added during this subsequent treatment. It is also simultaneously possible by means of this after treatment if desired, to convert the iron into special iron alloys, by the addition of sulphidic raw materials, for example M03 magnetic yrites containing nickel etc. The iron puri ed from this process still contains 0.3% S or more and must further be desul phurized in a subsequent operation according to own processes for example, electrolysis.- Whereas the ob ect he presout day metallurgy of iron is to effect an intensive desulphurization during the first smelting operation'by means of basic slags and intensive reduction and thus driving off the phosphorus content in the ore to a large extent into the iron, in the present rocess, on the other hand, no attention need e paid 'to the desulphurization in the first smelting Y operation but a high degree of dephosphorization can already first smeltin operation by the low degree of reduction .0 the slags (low consumption of coke) If desired, the operation may also be conducted to produce directly ironwith a low earbon content. ,Raw' iron comparatively ree impure iron ores containing sulphur with a be obtained if desired, in the bg thermoo t from manganese can be obta ned from 9 the matte to a large extent.

"the-metal phase, sulphide phase, slag phase,

. a suitably ered, entirely free from phosphorus, from ganese' content collects in the" desired and adjusted concentration in the sulphide phase and can subsequently be recovthe latter in a known manner. This sulph1d1c manganese materlal can be converted intohigh grade oxidic manganese material 'by subsequently roasting and sintering. Im-- pure chromium ores can be treated in a similar manner, slnce chromium also collects m The extent of A further very importantfield of application of the process in' the iron industry is that of a complementary operation to such known rocesses for working up sulphidic iron ores or which per se no practical use could be found owing to the fact that they yield a raw iron toorich in sulphur with the means hitherto available in practice. By subses -quently treating such ores in a three phase system according to the present process, iron v sulphide can be removed from iron thus produced, up to a remainder of 0.3% S. An imortant instance is the reduction of iron oxide y means of iron sulphide according to the well known reactions: 1

' 1. 2290 f-I-FeS fiFe-l-SO; +78 kg. ca].

By this means iron with a low carbon content and concentrated SO are obtained. It is proposed in a Norwegian specification to cause pure oxidic iron ore gfree from gangue) to react with pure iron su phide for the purpose ofproducing iron. The reason for" which this roposal has not been carried into practical e ect-may probably be due to the fact that even when using pure starting mate rials, the aforesaidreactions do not proceed sufliciently' to completion at temperatures which are economical and practically available so as to produce iron, which is sufliciently free form S. According to the degree of the temperature employed, a sulphur content of 2 to 10% remains behind in the iron, the removal of. which with the A means. hitherto available is too expensive. By combining this recess with the present invention a relative independenceof the degree of desulphurization in the first process is attained, since by subsequent treatment of the ,resulting iron which contains sulphur, in a three phase systam-"Witha sulphide phase containing. light a metal, the result isachieved'of decreasingthe content of iron sulphide in the iron to about 0.5%. Since in this embodiment, a very high degree ofdesulphurization is not necessary inthe first operation, low temperatures are suflicient. and the ,ores can advantageously b one operation employed vantage that a fractional precipitation of metal from sulphide is incidentally attained at the same time. If a low copper content is present as for example in Norwegian pyrites and burnt pyrites, this collects mainly in the sulphide phase during the second operation. This fractional recovery is still more important in the case of other more complex material and in such case the slag can a utilized for the fractional collection of certain components. Taking into, account the previous explanation,

Another known process which leads to the production of iron containing sulphur in a similar manner is the direct thermal decomosition of FeS into iron and sulphur. FeS 1s stable up .to about 1700 ;C., and .at increasing temperatures amounts of sulphur so that solutions of Fe in Fe ofdifierent composition are pr according to the temperatures employed. These can be divided into sulphide phase and metal base in exactly the same manner as explaine with reference to the preceding with their usual content of gangua. This embodiment has the further great adover the direct desulphurization in the possibilities in this con-, nection can be immediately seen from theoduced;

lsobe gives off increasing process'and either in the same apparatus 1 (simultaneously) or one after the other Elementary sulphur is obtained as a by-product. This process may also be combined with the preceding one if desired, and both S and S0 maybe produced.-

The process may be carried into practlcal effect in any known metallurgical furnace, I

the operation the aim however being to alter of the furnace andthe course of the process without making many alterations in the apparatus. Both shaft furnaces, reverberatory furnaces and electrical furnaces may be employed'with advantage the. apparatus being in each case selected to suit the particular purpose. It should however be remarked that electric fusion isparticularly suitable for this purpose, and in particular, electrode furnaces with a deep slag bath as resistance with or hout an are between the slag bath and. theelectrodes, since such an arrangement furnishes the maximum temperature in the slag where it is most desired and can best be sustained. Such an arrangement is should not esceed 1250 C. Even in cases wherethe process is carried out in shaft'furnaces or reverberatory furnaces, electric furin cases where the content of below 15% produce a it is intended to heavy metal dxides are duced in situ naces can be employed as fore-hearths of the t pe which have an extremely favourable inuence on the artition of the metal between the phases an are practically indispensable different .phases, either together or each separately, are intended to be subjected to a treatment with .difierent raw ferrous metals. As a matter of fact it has been found that in a three phase stem where divide up .aused liquid solution of metal and sulphide} into two phases by the addition of 1i htmetal sulphide, this division is efiecterf more rapidly and cleanly if this an electric current. I c1a1m:- 1. 'A process for smelting ores and other system is subjected to the electrolytic action 0 metallurgical products which comprises pro ducing a polyphase system including the phases slag, matte and metal; by areduction smelting in the presence of light metal compounds, the amount of light metal compounds and the extent of reduction being so regulated as to produce a slag havingan iron of FeO and a matte containing light metals.

"2. A process for smeltin ores and other metallurgical products whic comprises producing a polyphase system including the phases slag, matte and metal by a reduction smelting in the presence of light metal compounds, the amount of lightmetal compounds and the extentof reduction being so regulated as to produce a sla having an iron content of below 6% of Fe(% and a matte containing light metals.

3. A process for smelting ores and other metallurgical products which comprises pro ducing a polyphase system including the phases slag, matte and metal by a reduction smelting in the presence of-light metal compounds including alkali metal compounds, the amount of light metal compounds and the extent ofreduction being so regulated as to slag having an iron content of below 15% of FeO and a matte containing light metals. r

4. A process as defined in claim 1 wherein fides and transferred to the matte interaction witha sulfide of the metals, calcium and magn phase by interaction with a sulfide of at least one of the metals, calcium and magnesium, the sulfides of calcium and magnesium bein produced in situ during the process by action of carbonaceous material with the corresponding sulfates.

7. A process as defined in claim 1 wherein.

the charge and reduction is regulated to pro duce an acid slag.

8. A process as. defined in claim 1 wherein the charge and reduction is'regulated to produce an acid slag containing over 40% of silica.

9. A process as defined in claim 1 wherein such an amount of iron is rovided in the charge that a metallic iron p use is produced for the absorption of siderophilic elements.

10. A process as defined in claim 1 wherein such an amount of iron is provided in the charge that a metallic iron phase is produced for the absorption of siderophilic elements and the reduction is so carried out that metalloids of the group consisting of carbon, silicon and phosphorus are present in the iron phase. I

11. A process as defined in claim 1 wherein such an amount of iron is provided in the charge that a metallic iron phase is produced for the absor tion of siderophilic elements and substantially non ferrous speisses of metals non-miscible with iron are added to the charge whereby the metals non-miscible with iron contained in the non-ferous speisses atleast one of I are liberated by interaction production of an iron speiss.

12. A metallurgical. products which comprises producing a polyphase system including i the phases slag, matte and metal by a reduction smelting in the presence of compounds of metals whose sulfides have heats of formation of over 40 kg.'cal. per gram atom of sulfur, the amount of said metal compounds and the exthe mterwith the iron and process for smelting ore and other tent of reduction being so regulated as to produce a slag having an iron content of below 15% of FeO and a matte containing the sulfides of said metals.

'Intestimony whereof I my signature.

I SKAPPEL.

converted into sul- 5. A process as defined in claim 1 wherein heavy metal oxides are converted into sulfides and transferred tothe matte interaction with phase by a sulfide of at least one of the metals, calcium and magnesium, the sul-' fides of calcium and magnesium being produring the process 6.,A process as defined in claiin 1 wherein 1 heavy metal-oxides are converted into 5111- fides and transferred to the matte phase by Certificate fif Correctiori PatentN0'.1,797,700. w

" HARALD SKAPPEL It is hereby certifiedthat error appears in the printed spe'eifieation of the abevenumbered patent requiring. correction as follows: Page 7-, line 70,.for thevcharacter ""MGCOJ readeMg00 and line 124, for Na read Na fi; page 8, line 48, for

A1 0 readALO- and 1ine'1l6, forAlO O read AZ O page-10, line 90, for

v awed March24,1931,to

1.8 read 1:8; page 11, line 103, for Fe, 17.1% read Fe,1?.15%; page 13', line 89,

in Equation 13; for 2811 read S'n-i-Q; and'that the Said Letters Patentshopld be readwith these correetlons therein that the same mayf'conform to'the record of thecase in the Patent Ofiice. 1

Signed and sealed this 5th day of May, A. D.'1931. [smn] I. I

M. J. MOORE,

Acting Uommissz'mwr of Patents. 

